Method of fabricating liquid for oxide thin film

ABSTRACT

A method of fabricating a liquid for an oxide thin film is provided, which includes mixing at least two kinds of dispersoids selected from the group consisting of a Zinc compound, an Indium compound, a Gallium compound, a Tin compound and a Thallium compound, with dispersion media corresponding to the selected dispersoids to form a dispersion system, and stirring and aging the dispersion system at a predetermined temperature for a predetermined time, wherein a molar ratio of the Zinc compound to each of the Indium compound, Gallium compound, Tin compound and Thallium compound is 1:0.1 to 1:2. According to the present invention, the liquid for the oxide thin film may be fabricated by a sol-gel method making it capable of being implemented in mass production in a simple and low-cost manner as opposed to the conventional vacuum deposition method.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/739,657, filed Apr. 23, 2010, which is a U.S. National Stage ofInternational Application No. PCT/KR2008/000864 filed on Feb. 14, 2008,which claims priority from Korean Patent Application No. 10-2007-0107336filed on Oct. 24, 2007, the disclosures of each of which are herebyincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a method of fabricating a liquid for anoxide thin film, and more particularly, to a method of fabricating aliquid for an oxide thin film using a sol-gel method capable ofimplementing mass production.

BACKGROUND ART

Recently, oxide thin films have been usefully employed in displays andsemiconductor devices. In particular, a Zinc Oxide (ZnO) is a II-VIgroup direct transition semiconductor and has a high band gap of 3.37 eVso that it is transparent in a visible light region. Also, the ZincOxide (ZnO) has an exciton bond energy of 60 meV and is thus widelyemployed as an optical element (see D. C. Look et al. “Recent advancesin ZnO materials and devices” Materials Science and Engineering: B 80,383, (2001)).

The Zinc Oxide may have n-type characteristics due to native defectssuch as interstitial Zinc and oxygen vacancies, and may changeelectrical properties up to 10⁻² to 10¹⁰ Ωm depending on processconditions. In this case, the electron concentration may be furtherincreased to use the Zinc Oxide as a transparent electrode, for whichIII-group elements or VII-group elements are doped thereinto, Gallium(Ga), Aluminum Al), and Indium (In), which belong to the III-group, arerepresentative dopants, and materials doped with Ga, Al, and In arenamed Gallium Zinc Oxide (GZO) (see Quan-Bao et al. “Structural,electrical, and optical properties of transparent conductive ZnO:Gafilms prepared by DC reactive magnetron sputtering” Journal of CrystalGrowth, 304, 64 (2007)), Aluminum Zinc Oxide (AZO) (see Byeong-Yun Oh etal. “Properties of transparent conductive ZnO:Al films prepared byco-sputtering” Journal of Crystal Growth, Volume 274, 453, (2005)), andIndium Zinc Oxide (IZO) (see E. J. Luna-Arredondo et al. “Indium-dopedZnO thin films deposited by the solgel technique” Thin Solid Films, 490,132 (2005)), respectively. These transparent electrodes have come intothe spotlight as materials capable of taking the place of transparentelectrodes formed of Indium Tin Oxides (ITO) which have been widelyapplied to electronic devices in recent years.

The transparency of ZnO enables it to be implemented in a transparenttransistor, and the high mobility of ZnO allows it to be used as anactive layer of the transistor of a display device. When ZnO is a bulk,it has a superior mobility of about 200 cm²/Vs (see D. C. Look et al.“Electrical properties of bulk ZnO” Solid State Commun. 105, 399(1998)). In addition, ZnO has an ionic bond so that a mobilitydifference between single crystalline ZnO and amorphous ZnO is notsignificant compared to Silicon (Si). Such properties allow it to beapplied to modern display devices which require an active layer havinghigh mobility. Furthermore, many other elements have been alloyed with aZinc compound in order to obtain a higher mobility and a stable activelayer. Materials having a greater orbital than the 5s-orbital of Zincand a larger ion radius than Zinc (e.g., Indium, Tin, Thallium) areadded to the Zinc compound to form alloys such as In—Ga—ZnO (IGZO),In—ZnO (IZO), Sn—ZnO (SZO), Sn—Ga—ZnO (SGZO), In—Sn—ZnO (ISZO), Tl—ZnO(TZO), and Tl—Ga—ZnO (TGZO). These material share more outermostelectrons of the 5s-orbital due to greater positive ions than Zinc,which contributes to the electron mobility. In this case, Gallium of theactive layer contributes to adjustment in electrical properties andenhancement of stability.

Currently, research is being performed particularly on IGZO using vacuumequipment associated with pulse laser deposition (PLD), sputtering,chemical vapor deposition (CVD) and so forth to be applied to variousdisplay devices. However, when such vacuum equipment is employed, theunit price of the process is increased due to the price of thelarger-sized equipment.

DISCLOSURE OF INVENTION Technical Problem

In order to solve the foregoing and/or other problems, it is anobjective of the present invention to provide a method of fabricating aliquid for an oxide thin film using a sol-gel method capable ofimplementing mass production.

Technical Solution

In one aspect, the invention is directed to a method of fabricating aliquid for an oxide thin film, which includes: mixing at least two kindsof dispersoids selected from the group consisting of a Zinc compound, anIndium compound, a Gallium compound, a Tin compound and a Thalliumcompound, with dispersion media corresponding to the selecteddispersoids to form a dispersion system; and stirring and aging thedispersion system at a predetermined temperature for a predeterminedtime, wherein a molar ratio of the Zinc compound to each of the Indiumcompound, Gallium compound, Tin compound and Thallium compound is 1:0.1to 1:2.

The dispersion media may include at least one selected from the groupconsisting of isopropanol, 2-methoxyethanol, dimethylformamide, ethanol,deionized water, methanol, acetylacetone, dimethylamineborane, andacetonitrile corresponding to the dispersoids. The Zinc compound mayinclude Zinc citrate dihydrate, Zinc acetate, Zinc acetate dihydrate,Zinc acetylacetonate hydrate, Zinc acrylate, Zinc chloride, Zincdiethyldithiocarbamate, Zinc dimethyldithiocarbamate, Zinc fluoride,Zinc fluoride hydrate, Zinc hexafluoroacetylacetonate dihydrate, Zincmethacrylate, Zinc nitrate hexahydrate, Zinc nitrate hydrate, Zinctrifluoromethanesulfonate, Zinc undecylenate, Zinc trifluoroacetatehydrate, Zinc tetrafluoroborate hydrate, or zinc perchloratehexahydrate. The Indium compound may include Indium chloride, Indiumchloride tetrahydrate, Indium fluoride, Indium fluoride trihydrate,Indium hydroxide, Indium nitrate hydrate, Indium acetate hydrate, Indiumacetylacetonate, or Indium acetate. The Gallium compound may includeGallium acetylacetonate, Gallium chloride, Gallium fluoride, or Galliumnitrate hydrate. The Tin compound may include Tin acetate, Tin chloride,Tin chloride dihydrate, Tin chloride pentahydrate, or Tin fluoride. TheThallium compound may include Thallium acetate, Thalliumacetylacetonate, Thallium chloride, Thallium chloride tetrahydrate,Thallium cyclopentadienide, Thallium fluoride, Thallium formate,Thallium hexafluoroacetylacetonate, Thallium nitrate, Thallium nitratetrihydrate, Thallium trifluoroacetate, or Thallium perchlorate hydrate.A molar concentration of each of the Zinc compound, Indium compound,Gallium compound, Tin compound and Thallium compound may be 0.1M to 10M.A sol stabilizer having substantially the same molar ratio as the Zinccompound may be mixed with the dispersion system. The sol stabilizer mayinclude at least one kind selected from the group consisting ofmono-ethanolamine, di-ethanolamine and tri-ethanolamine. An acid or basefor adjusting pH of the dispersion system may be added to the dispersionsystem. Acetic acid (CH₃COOH) may be added as the acid to the dispersionsystem to lower pH or ammonium hydroxide (NH₃OH), potassium hydroxide(KOH) or sodium hydroxide (NaOH) may be added as the base to thedispersion system to increase pH so that the pH range of the dispersionsystem is 1 to 10. The pH range of the dispersion system may be 3.8 to4.2. The dispersion system may be stirred at 25° C. to 100° C. forsubstantially 1 hour to 24 hours. The dispersion system may be aged forsubstantially 1 hour to 240 hours.

In another aspect, the invention is directed to a method of fabricatinga liquid for an oxide thin film, which includes: (a) mixing at least twokinds of dispersoids selected from the group consisting of a Zinccompound, an Indium compound, a Gallium compound, a Tin compound and aThallium compound, with dispersion media corresponding to the selecteddispersoids to form a dispersion system; and (b) stirring and aging thedispersion system at a predetermined temperature for a predeterminedtime, wherein a molar ratio of the Zinc compound to each of the Indiumcompound, Gallium compound, Tin compound and Thallium compound is 1:0.1to 1:2, the dispersion media comprise at least one selected from thegroup consisting of isopropanol, 2-methoxyethanol, dimethylformamide,ethanol, deionized water, methanol, acetylacetone, dimethylamineborane,and acetonitrile corresponding to the dispersoids, and a molarconcentration of each of the Zinc compound, Indium compound, Galliumcompound, Tin compound and Thallium compound is substantially 0.1M to10M.

Advantageous Effects

According to the present invention as described above, a method offabricating an oxide thin film such as IZO, IGZO, ISZO, SZO, SGZO, TGZO,TZO which are being actively researched for display and semiconductordevices, may be executed by a sol-gel method making it capable of beingimplemented in mass production in a simple and low-cost manner asopposed to the conventional vacuum deposition method.

In addition, the oxide thin film fabricated by a method of fabricating aliquid according to exemplary embodiments of the present invention maybe applied to display devices such as organic light emitting diodes(OLEDs) and liquid crystal displays (LCDs), or solar cells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating XPS (X-ray photoelectron spectroscopy)results of an Indium-Gallium-Zinc oxide (IGZO) thin film formed byIndium-Gallium-Zinc oxide sol in a method of fabricating a liquid for anoxide thin film according to exemplary embodiments of the presentinvention.

FIG. 2 illustrates XPS results of In 3d_(5/2) region in the IGZO thinfilm shown in FIG. 1.

FIG. 3 illustrates XPS results of Ga 2p_(3/2) region in the IGZO thinfilm shown in FIG. 1.

FIG. 4 illustrates XPS results of Zn 2p_(3/2) region in the IGZO thinfilm shown in FIG. 1.

FIG. 5 illustrates an O 1s peak as XPS results of in the IGZO thin filmshown in FIG. 1.

MODE FOR THE INVENTION

Hereinafter, exemplary embodiments of the present invention will bedescribed with reference to the accompanying drawings. In thedescription of the present invention, when the detailed description offunctionalities of components or related well-known components mayobfuscate the spirit of the present invention, the description thereofwill be omitted.

A method of fabricating a liquid for an oxide thin film according to thepresent exemplary embodiment includes: mixing at least two kinds ofdispersoids selected from the group consisting of a Zinc compound, anIndium compound, a Gallium compound, a Tin compound and a Thalliumcompound, with dispersion media corresponding to the selecteddispersoids to form a dispersion system; and stirring and aging thedispersion system at a predetermined temperature for a predeterminedtime. Meanwhile, molar ratios of the Zinc compound to each of the Indiumcompound, Gallium compound and Thallium compound are substantially 1:0.1to 1:2. In this case, when the molar ratios of the Zinc compound to theother illustrated compounds are substantially less than 1:0.1, thecompounds act as only a transparent electrode due to a doping effect,and when the molar ratios of the Zinc compound to the other illustratedcompounds are substantially greater than 1:2, these other compounds aremixed with the Zinc compound to form an alloy so that an amorphous oxidethin film having high mobility can be produced. However, the othercompounds are main components so that the other compounds cannot befundamental materials for allowing the Zinc compound to have anamorphous structure. Accordingly, it is obvious that the molar ratio ofthe Zinc compound to each of the Indium compound, Gallium compound, Tincompound and Thallium compound, that is, 1:0.1 to 1:2, are preferablefor making an alloy with the Zinc compound.

In this case, the dispersion medium may include at least one selectedfrom the group consisting of isopropanol, 2-methoxyethanol,dimethylformamide, ethanol, deionized water, methanol, acetylacetone,dimethylamineborane, and acetonitrile.

In addition, the Zinc compound may include Zinc citrate dihydrate, Zincacetate, Zinc acetate dihydrate, Zinc acetylacetonate hydrate, Zincacrylate, Zinc chloride, Zinc diethyldithiocarbamate, Zincdimethyldithiocarbamate, Zinc fluoride, Zinc fluoride hydrate, Zinchexafluoroacetylacetonate dihydrate, Zinc methacrylate, Zinc nitratehexahydrate, Zinc nitrate hydrate, Zinc trifluoromethanesulfonate, Zincundecylenate, Zinc trifluoroacetate hydrate, Zinc tetrafluoroboratehydrate, or Zinc perchlorate hexahydrate.

The Indium compound may include Indium chloride, Indium chloridetetrahydrate, Indium fluoride, Indium fluoride trihydrate, Indiumhydroxide, Indium nitrate hydrate, Indium acetate hydrate, Indiumacetylacetonate, or Indium acetate.

The Gallium compound may include Gallium acetylacetonate, Galliumchloride, Gallium fluoride, or Gallium nitrate hydrate.

The Tin compound may include Tin acetate, Tin chloride, Tin chloridedihydrate, Tin chloride pentahydrate, or Tin fluoride.

The Thallium compound may include Thallium acetate, Thalliumacetylacetonate, Thallium chloride, Thallium chloride tetrahydrate,Thallium cyclopentadienide, Thallium fluoride, Thallium formate,Thallium hexafluoroacetylacetonate, Thallium nitrate, Thallium nitratetrihydrate, Thallium trifluoroacetate, or Thallium perchlorate hydrate.

Meanwhile, the molar ratio of each of the Zinc compound, Indiumcompound, Gallium compound, and Thallium compound may be 0.1M (mol/L) to10M (mol/L).

In addition, a sol stabilizer having substantially the same molar ratioas the Zinc compound illustrated above may be mixed with the dispersionsystem. For example, the sol stabilizer may include at least oneselected from the group consisting of mono-ethanolamine, di-ethanolamineand tri-ethanolamine.

The hydrogen ion exponent of the dispersion system, i.e., pH may beadjusted to add a small amount of acid or base to the mixed dispersionsystem until the dispersion system is transparent and uniform. Forexample, acetic acid (CH₃COOH) may be added as the acid to thedispersion system to lower pH or ammonium hydroxide (NH₃OH), potassiumhydroxide (KOH) or sodium hydroxide (NaOH) may be added as the base tothe dispersion system to increase pH so that the pH range of thedispersion system is 1 to 10. Preferably, the pH range of the dispersionsystem may be 3.8 to 4.2.

As described above, after the dispersion system is formed, thedispersion system is stirred at a temperature of 25° C. to 100° C. forsubstantially 1 hour to 24 hours, and then aged for substantially 1 hourto 240 hours to form corresponding IGZO, IZO, SZO, SGZO, ISZO, TZO, orTGZO.

Hereinafter, exemplary embodiments of the method of fabricating a liquidfor an oxide thin film according to the present invention will bedescribed.

First, an exemplary embodiment for forming an IGZO sol will be describedas follows.

A 2-methoxyethanol dispersion medium of 20 ml is mixed with a dispersoidcontaining Zinc acetate dihydrate with substantially 0.7 molarconcentration, and a deionized water dispersion medium of 20 mlcontaining ethanol is mixed with Gallium nitrate hydrate and Indiumnitrate hydrate dispersoids to form a dispersion system.Mono-ethanolamine having substantially the same molar ratio as the Zincacetate dihydrate is then added by a small amount to the already mixeddispersion system. As a result, a milky dispersion system is formed, andan acid, for example, acetic acid, is added thereto by a small amount tomake the milky dispersion system transparent and uniform. Meanwhile, pHof the uniform sol is substantially 3.8 to 4.2. The dispersion system isthen stirred at 60° C. for 1 hour in a hot plate, and is aged for 24hours to form a uniform, stable, and aged dispersion system.Accordingly, the IGZO sol is formed.

Second, another exemplary embodiment for forming an IGZO sol will bedescribed as follows.

A deionized water dispersion medium of 40 ml containing methanol ismixed with dispersoids containing Zinc nitrate hexahydrate, Galliumnitrate hydrate and Indium nitrate hydrate each having substantially 0.7molar concentration to form a dispersion system. The dispersion systemis then stirred at 60° C. for 1 hour in a hot plate, and is aged for 24hours to form a stable and aged dispersion system. Accordingly, the IGZOsol is formed.

Third, still another exemplary embodiment for forming an IGZO sol willbe described as follows.

A deionized water dispersion medium of 40 ml containing methanol ismixed with dispersoids containing Zinc acetate dihydrate, Galliumnitrate hydrate and Indium nitrate hydrate each having substantially 0.7molar concentration to form a dispersion system. An acid, for example,acetic acid, is then added by a small amount to make the dispersionsystem transparent and uniform. In this case, pH of the uniform sol issubstantially 3.8 to 4.2. The dispersion system is then stirred at 60°C. for 1 hour in a hot plate, and is aged for 24 hours to form auniform, stable and aged dispersion system. Accordingly, the IGZO sol isformed.

Fourth, yet another exemplary embodiment for forming an IGZO sol will bedescribed as follows.

An acetonitrile dispersion medium of 40 ml is mixed with dispersoidscontaining Zinc chloride, Gallium chloride, and Indium chloride eachhaving substantially 0.5 or 0.7 molar concentration to form a dispersionsystem. The dispersion system is then stirred at 60° C. for 1 hour in ahot plate, and is aged for 24 hours to form a uniform, stable and ageddispersion system. Meanwhile, since the Zinc chloride, Gallium chloride,and Indium chloride are very susceptible to moisture, the process may becarried out within a moistureless glove box where the moisture may beeasily adjusted. Accordingly, the IGZO sol is formed.

A process of fabricating a thin film using the IGZO sol formed by thedescribed exemplary embodiments will be illustrated as follows.

First, spin-coating is performed at a speed of 3000 rpm and than athermal treatment is performed at 600° C. for 1 hour in the air.

Meanwhile, FIG. 1 is a graph illustrating XPS results of the IGZO thinfilm formed by the IGZO sol in the method of fabricating the liquid foran oxide thin film according to the present exemplary embodiment. Inthis case, a reference peak is set to C 1s 285 eV. Peaks of Indium,Gallium, Zinc, Oxygen, and a small amount of Chlorine are represented inthe formed IGZO thin film. As shown in FIG. 1, rates of the elements,i.e., Indium, Gallium, Zinc, and Oxygen, are 15.39%, 12.67%, 15.45%, and56.49%, respectively. That is, it can be seen that the IGZO thin film isformed.

For reference, detailed chemical reactions regarding the formation ofthe IGZO thin film are as follows.ZnCl₂+InCl₃GaCl₃→Zn(OH)Cl+In(OH)₂Ga(OH)₃+HCl(↑)  Chemical formula 1

(IGZO thin film at room temperature)ZnCl₂+InCl₃GaCl₃→Zn(OH)Cl+In₂O₃+Ga₂O₃+H₂O(↑)  Chemical formula 2

(IGZO thin film at substantially 100° C. to 150° C.)ZnCl₂+InCl₃+GaCl₃→ZnO—In₂O₃—Ga₂O₃+ZnCl₂(↑)+HCl(↑)+H₂O(↑)  Chemicalformula 3

(IGZO thin film at substantially 400° C. to 600° C.)

FIGS. 2 to 5 illustrate XPS results of the respective element regions inthe XPS graph of FIG. 1. That is, FIG. 2 illustrates XPS results of In3d_(3/2) region in the IGZO thin film, FIG. 3 illustrates XPS results ofGa 2p_(3/2) region in the IGZO thin film, and FIG. 4 illustrates XPSresults of Zn 2p_(3/2) region in the IGZO thin film.

Meanwhile, FIG. 5 illustrates an O 1s peak as XPS results in the IGZOthin film. The O 1s peak is divided into three peaks by means ofGaussian fitting. That is, O_(I) (530.5±0.3 eV) indicates In—O, Ga—O,and Zn—O bonds in the IGZO structure, O_(II) (531.5±0.3 eV) indicatesoxygen vacancies in the IGZO structure, and O_(III) (532.5±0.3 eV)indicates oxygen weakly isolated in the surface of the IGZO thin film.Kinds thereof include adsorbed —CO₃, H₂O or O₂, and the respective ratesare O_(I)/O_(tot) (57.29%), O_(II)/O_(tot) (22.69%), and O_(III)/O_(tot)(20.02%). Accordingly, it can be seen that the IGZO thin film has a goodchemical bond since rates of In—O, Ga—O, and Zn—O are less than theoxygen vacancies.

Fifth, an exemplary embodiment for forming an IZO sol will be describedas follows.

An acetonitrile dispersion medium of 40 ml is mixed with dispersoidscontaining Zinc chloride and Indium chloride each having substantially0.5 or 0.7 molar concentration to form a dispersion system. Thedispersion system is then stirred at 60° C. for 1 hour in a hot plate,and aged for 24 hours to form a uniform, stable and aged dispersionsystem. Meanwhile, since the Zinc chloride and Indium chloride are verysusceptible to moisture, the process may be carried out within amoistureless glove box where the moisture may be easily adjusted.Accordingly, the IZO sol is formed.

Sixth, another exemplary embodiment for forming an IZO sol will bedescribed as follows.

A 2-methoxyethanol dispersion medium of 20 ml is mixed with dispersoidscontaining Zinc acetate dihydrate and Indium acetate hydrate each havingsubstantially 0.5 or 0.7 molar concentration to form a dispersionsystem. A sol stabilizer, i.e., mono-ethanolamine having substantiallythe same molar ratio as Zinc acetate dihydrate, is then mixed with theformed dispersion system. The dispersion system is then stirred at 60°C. for 1 hour in a hot plate, and is aged for 24 hours to form auniform, stable and aged dispersion system. Accordingly, the IZO sol isformed.

Seventh, an exemplary embodiment for forming an SZO sol will bedescribed as follows.

A 2-methoxyethanol dispersion medium of 20 ml is mixed with dispersoidscontaining Zinc acetate dihydrate and Tin acetate each havingsubstantially 0.7 molar concentration to form a dispersion system. A solstabilizer, i.e., mono-ethanolamine having substantially the same molarratio as Zinc acetate dihydrate, is then mixed with the formeddispersion system. The dispersion system is then stirred at 60° C. for 1hour in a hot plate, and is aged for 24 hours to form a uniform, stableand aged dispersion system. Accordingly, the SZO sol is formed.

Eighth, another exemplary embodiment for forming an SZO sol will bedescribed as follows.

An acetonitrile dispersion medium of 40 ml is mixed with dispersoidscontaining Zinc chloride and Tin chloride each having substantially 0.5or 0.7 molar concentration to form a dispersion system. The dispersionsystem is then stirred at 60° C. for 1 hour in a hot plate, and is agedfor 24 hours to form a uniform, stable and aged dispersion system. Inthis case, since the Zinc chloride and Tin chloride are very susceptibleto moisture, the process may be carried out within a moistureless glovebox where the moisture may be easily adjusted. Accordingly, the SZO solis formed.

Ninth, an exemplary embodiment for forming an ISZO sol will be describedas follows.

An acetonitrile dispersion medium of 40 ml is mixed with dispersoidscontaining Zinc chloride, Tin chloride, and Indium chloride each havingsubstantially 0.5 or 0.7 molar concentration to form a dispersionsystem. The dispersion system is then stirred at 60° C. for 1 hour in ahot plate, and is aged for 24 hours to form a uniform, stable and ageddispersion system. In this case, since the Zinc chloride, Tin chloride,and Indium chloride are very susceptible to moisture, the process may becarried out within a moistureless glove box where the moisture may beeasily adjusted. Accordingly, the ISZO sol is formed.

Tenth, another exemplary embodiment for forming an ISZO sol will bedescribed as follows.

A 2-methoxyethanol dispersion medium of 40 ml is mixed with dispersoidscontaining Zinc acetate dihydrate, Tin acetate, and Indium acetatehydrate each having substantially 0.7 molar concentration to form adispersion system. A sol stabilizer, i.e., mono-ethanolamine havingsubstantially the same molar ratio as Zinc acetate dihydrate is thenmixed with the formed dispersion system. The dispersion system is thenstirred at 60° C. for 1 hour in a hot plate, and is aged for 24 hours toform a uniform, stable and aged dispersion system. Accordingly, the ISZOsol is formed.

Eleventh, an exemplary embodiment for forming an SGZO sol will bedescribed as follows.

An acetonitrile dispersion medium of 40 ml is mixed with dispersoidscontaining Zinc chloride, Tin chloride, and Gallium chloride each havingsubstantially 0.5 or 0.7 molar concentration to form a dispersionsystem. The dispersion system is then stirred at 60° C. for 1 hour in ahot plate, and is aged for 24 hours to form a uniform, stable and ageddispersion system. In this case, since the Zinc chloride, Tin chloride,and Gallium chloride are very susceptible to moisture, the process maybe carried out within a moistureless glove box where the moisture may beeasily adjusted. Accordingly, the SGZO sol is formed.

Twelfth, an exemplary embodiment for forming a TZO sol will be describedas follows.

A 2-methoxyethanol dispersion medium of 20 ml is mixed with dispersoidscontaining Zinc acetate dihydrate and Thallium acetate each havingsubstantially 0.7 molar concentration to form a dispersion system. A solstabilizer, i.e., mono-ethanolamine having substantially the same molarratio as Zinc acetate dihydrate is then mixed with the formed dispersionsystem. The dispersion system is then stirred at 60° C. for 1 hour in ahot plate, and is aged for 24 hours to form a uniform, stable and ageddispersion system. Accordingly, the TZO sol is formed.

Thirteenth, another exemplary embodiment for forming a TZO sol will bedescribed as follows.

An acetonitrile dispersion medium of 20 ml is mixed with dispersoidscontaining Zinc chloride and Thallium chloride each having substantially0.5 or 0.7 molar concentration to form a dispersion system. Thedispersion system is then stirred at 60° C. for 1 hour in a hot plate,and is aged for 24 hours to form a uniform, stable and aged dispersionsystem. In this case, since the Zinc chloride and Thallium chloride arevery susceptible to moisture, the process may be carried out within amoistureless glove box where the moisture may be easily adjusted.Accordingly, the TZO sol is formed.

Fourteenth, an exemplary embodiment for forming a TGZO sol will bedescribed as follows.

An acetonitrile dispersion medium of 40 ml is mixed with dispersoidscontaining Zinc chloride, Thallium chloride, and Gallium chloride eachhaving substantially 0.5 or 0.7 molar concentration to form a dispersionsystem. The dispersion system is then stirred at 60° C. for 1 hour in ahot plate, and is aged for 24 hours to form a uniform, stable and ageddispersion system. In this case, since the Zinc chloride, Thalliumchloride, and Gallium chloride are very susceptible to moisture, theprocess may be carried out within a moistureless glove box where themoisture may be easily adjusted. Accordingly, the TGZO sol is formed.

Meanwhile, in the exemplary embodiments described above, the molarconcentration of the dispersoid mixed with the dispersion mediumdetermines a thickness of the thin film when the resultant sol isproduced to be thin-filmed. For example, it is difficult to form thethin film when the molar concentration of the dispersoid is much lowerthan the molar concentrations illustrated in the respective exemplaryembodiments, and the dispersoid has a solubility greater than that ofthe dispersion medium causing precipitation when the molar concentrationof the dispersoid is much higher than the molar concentrationsillustrated in the respective exemplary embodiments, so that it ispreferable to set molar concentrations of the dispersoids suitable forthe respective exemplary embodiments.

Exemplary embodiments of the present invention have been disclosed withrespect to a method of fabricating a liquid for an oxide thin film and,although specific terms are employed, they are used and are to beinterpreted in a generic and descriptive sense only and not for purposeof limitation. Accordingly, it will be understood by those of ordinaryskill, in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

The invention claimed is:
 1. A liquid for an oxide thin film comprising:a first compound selected from a zinc compound; a second compoundselected from the group consisting of an indium compound, a galliumcompound, a tin compound, a thallium compound and combinations thereof;and a stabilizer having substantially the same molar ratio as the zinccompound, wherein a molar ratio of the first compound to the secondcompound is 1:0.1 to 1:2.
 2. The liquid according to claim 1, wherein amolar concentration of each of the first compound and the secondcompound is 0.1M to 10M.
 3. The liquid according to claim 2, wherein thezinc compound comprises zinc citrate dihydrate, zinc acetate, zincacetate dihydrate, zinc acetylacetonate hydrate, zinc acrylate, zincchloride, zinc diethyldithiocarbamate, zinc dimethyldithiocarbamate,zinc fluoride, zinc fluoride hydrate, zinc hexafluoroacetylacetonatedihydrate, zinc methacrylate, zinc nitrate hexahydrate, zinc nitratehydrate, zinc trifluoromethanesulfonate, zinc undecylenate, zinctrifluoroacetate hydrate, or zinc tetrafluoroborate hydrate zincperchlorate hexahydrate.
 4. The liquid according to claim 2, wherein theindium compound comprises indium chloride, indium chloride tetrahydrate,indium fluoride, indium fluoride trihydrate, indium hydroxide, indiumnitrate hydrate, indium acetate hydrate, indium acetylacetone or indiumacetate.
 5. The liquid according to claim 2, wherein the tin compoundcomprises tin acetate, tin chloride, tin chloride dehydrate, tinchloride pentahydrate, or tin fluoride.
 6. The liquid according to claim2, wherein the thallium compound comprises thallium acetate, thalliumacetylacetone, thallium chloride, thallium chloride tetrahydrate,thallium cyclopentadienide, thallium fluoride, thallium formate,thallium hexafluoroacetylacetonate, thallium nitride, thallium nitratetrihydrate, thallium trifluoroacetate, or thallium perchlorate hydrate.7. The liquid according to claim 1, wherein the stabilizer comprisesmono-ethanolamine, di-ethanolamine, tri-ethanolamine or combinationsthereof.
 8. The liquid according to claim 1, wherein the zinc compoundcomprises zinc citrate dihydrate, zinc acetate, zinc acetate dihydrate,zinc acetylacetonate hydrate, zinc acrylate, zinc chloride, zincdiethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc fluoride,zinc fluoride hydrate, zinc hexafluoroacetylacetonate dihydrate, zincmethacrylate, zinc nitrate hexahydrate, zinc nitrate hydrate, zinctrifluoromethanesulfonate, zinc undecylenate, zinc trifluoroacetatehydrate, or zinc tetrafluoroborate hydrate zinc perchlorate hexahydrate.9. The liquid according to claim 8, wherein the stabilizer comprisesmono-ethanolamine, di-ethanolamine, tri-ethanolamine or combinationsthereof.
 10. The liquid according to claim 1, wherein the indiumcompound comprises indium chloride, indium chloride tetrahydrate, indiumfluoride, indium fluoride trihydrate, indium hydroxide, indium nitratehydrate, indium acetate hydrate, indium acetylacetone or indium acetate.11. The liquid according to claim 1, wherein the tin compound comprisestin acetate, tin chloride, tin chloride dehydrate, tin chloridepentahydrate, or tin fluoride.
 12. The liquid according to claim 1,wherein the thallium compound comprises thallium acetate, thalliumacetylacetone, thallium chloride, thallium chloride tetrahydrate,thallium cyclopentadienide, thallium fluoride, thallium formate,thallium hexafluoroacetylacetonate, thallium nitride, thallium nitratetrihydrate, thallium trifluoroacetate, or thallium perchlorate hydrate.13. The liquid according to claim 1, further comprising solvents for thefirst and the second compounds, the solvent being selected from thegroup consisting of isopropanol, 2-methoxyethanol, dimethylformamide,ethanol, deionized water, methanol, acetylacetone, dimethylamineborane,and acetonitrile.
 14. A liquid for an oxide thin film comprising: afirst compound selected from a zinc compound; a second compound selectedfrom the group consisting of an indium compound, a gallium compound, atin compound, a thallium compound and combinations thereof; and a pHcontrolling agent for adjusting pH of the liquid, wherein the pHcontrolling agent comprises acetic acid, ammonium hydroxide, potassiumhydroxide, or sodium hydroxide, and wherein a molar ratio of the firstcompound to the second compound is 1:0.1 to 1:2.
 15. A method of formingan oxide film comprising: preparing an oxide liquid; and depositing theoxide liquid, wherein preparing the oxide liquid comprising: mixing afirst compound selected from a zinc compound, a second compound selectedfrom the group consisting of an indium compound, a gallium compound, atin compound, a thallium compound and combinations thereof, and astabilizer having substantially the same molar ratio as the zinccompound, wherein a molar ratio of the first compound to the secondcompound is 1:0.1 to 1:2.
 16. The method according to claim 15, whereina molar concentration the first compound is 0.1M to 10M and a molarconcentration of the second compound is 0.1M to 10M.